Swiss banks may cut more jobs and increase fees as tougher regulations and lower margins put them under pressure, according to an industry group.

Banks’ share of Swiss gross domestic product will probably continue declining until at least 2015, after falling to 6.1 percent in 2011 from 8 percent in 2007, the Basel-based Swiss Bankers Association said in a study based on calculations from BAK Basel Economics AG, an economic research institute.

Should tax and other regulations evolve unfavorably, “everyone will feel the impact of this in the form of fewer jobs, lower tax revenue and more expensive banking services,” SBA Chief Executive Officer Claude-Alain Margelisch said in an e-mailed statement. “The financial center is of crucial importance to the Swiss economy.”

The association forecasts a 0.3 percent annual decline in the 146,000 Swiss banking jobs until 2020. Banking industry growth, which outpaced the wider national economy over the past 20 years, may slow in 2012 and 2013, according to the SBA, which has 347 members, including UBS AG and Credit Suisse Group AG.

By cutting expenses, including wages, and boosting revenue, Swiss banks improved their average cost-to-income ratio, a measure of financial strength, to 68.3 percent in 2011, from 82.4 percent in 2008, according to the study.